He said: "Our relationship has just grown deeper and more interesting. We love each other and we love the journey we're taking together and that's not a cliche.
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"We are both actively engaged in each other's lives and we both find that it's so beautiful to be able to appreciate each other in new and different ways. We both see marriage as an active and evolving bond between us."
Ashton – who, at 33, is 15 years younger than Demi - credits his successful marriage to communicating honestly and surprising his wife whenever he can.
He added in an interview with Britain's OK! magazine: "You have to be very serious about communicating your feelings and just expressing yourself and being open to your partner.
"Demi and I both believe in that kind of philosophy. We also like being romantic and doing special little things for each other, whether it's coming up with a wild new meal for dinner or suggesting a trip somewhere.
"You don't want to just sit around and get into some routine where you don't even realise that you've fallen into that kind of thing."